In self-feathering propellers used on auxiliary powered vessels the blades are constructed and arranged for limited rotation about individual axes normal to the axis of the propeller shaft. Various constructions of such propellers have been proposed heretofore.
In J. M. Casey U.S. Pat. No. 1,718,525, June 25, 1929, the propeller blades are journaled on eccentric axes in a split casing which is attached to the propeller shaft. The blades are provided with flanged base portions which serve as bearing surfaces and the blades are rotated about their axes by cooperating lugs and helical ribs provided on the flanged base portions and the shaft. Such blade-base-bearings, generally referred to as "table bearings" are notoriously troublesome when the load is applied at some distance from the bearing surfaces.
In M. D. Thompson U.S. Pat. Nos. 2,134,157, Oct. 25, 1938, and 2,283,774, May 10, 1942, the blades also are provided with flanged base portions serving as bearing surfaces. The blades are rotated about their axes by means of lugs extending from the base portions and slidably received in helical grooves formed in the peripheral surface of the propeller shaft.
In the prior devices, the propeller blades are rotated about their axes to working pitch positions by mechanical force. The operating principle is that of a cam and cam follower, requiring precision machining of the co-acting parts. In general, the prior devices are complex and costly and have a low reliability factor.
A self-feathering propeller made in accordance with this invention requires a minimum number of simple, sturdy parts which are loosely fitted together to provide an operative assembly.